Where does the path of electrical depolarization in the heart originate?

The path of electrical depolarization in the heart originates at the sinoatrial (SA) node. This structure, often referred to as the natural pacemaker of the heart, is located in the right atrium. It generates electrical impulses that initiate the heartbeat and set the rhythm for the entire heart.

When the SA node fires, it causes the atria to depolarize and contract, pushing blood into the ventricles. This electrical signal then travels to the atrioventricular (AV) node, where there is a brief delay before the signal continues to the Bundle of His and subsequently to the Purkinje fibers, resulting in ventricular contraction.

The other options refer to components of the conduction system that play important roles in the spread of electrical signals throughout the heart but do not initiate the electrical depolarization. The AV node serves as a relay point that allows for optimal timing of contractions, the Bundle of His transmits impulses from the AV node to the ventricles, and the Purkinje fibers distribute the electrical impulses throughout the ventricles to ensure coordinated contraction. However, it is the SA node that is the starting point of the electrical activity in a healthy heart.